1. Field of Invention
The present invention relates generally to wiper systems, and more specifically, to a wiper motor drive system having a breakaway clutch.
2. Description of Related Art
Conventional automotive wiper systems known in the art typically include some type of wiper blade (sometimes referred to as a wiper assembly) mounted to a wiper arm which, in turn, is mounted adjacent to a surface to be wiped, such as the windshield or the rear window of a vehicle, and pivotally driven by a wiper motor drive system to impart reciprocal motion to the wiper blade across the window. Modern wiper motor drive systems known in the art typically include a motor, a transmission (sometimes referred to as a gear set or linkage), and an output shaft, wherein the transmission translates rotational movement from the motor to the output shaft, which drives the wiper arm and wiper blade.
Each of the components of a wiper motor drive system of the type described above must cooperate to effectively translate rotational movement from the motor to the output shaft, so as to ensure a consistent and effective wipe. Further, there is a desire to reduce the weight of automotive components, as lower total vehicle weight equates to improved fuel economy. Thus, wiper motor drive systems must be designed not only to facilitate consistent wipe quality, but also in such a way so as to reduce overall weight, geometry, and manufacturing cost. Consequently, there is a trend in the art of utilizing smaller, lighter wiper motor drive systems having smaller motors and transmissions. Typically, these systems include smaller, lighter components that are relatively weaker than components used in larger, conventional wiper motor drive systems.
Particularly with respect to rear window wiper motor drive systems, there is a concern of external forces acting on the wiper arm or wiper blade and damaging the components of the wiper motor drive system. By way of example, external torque or resistance may be applied to the wiper blade or arm due to: ice buildup, caught cleaning implements (such as in a drive-through car wash), grabbing or pulling of the wiper arm by a child, incorrect handling during wiper blade replacement, etc.
Thus, there remains a need in the art for a wiper motor drive system that has superior operational characteristics, reduced weight and dimensions, and that can withstand torque applied by external or environmental forces.